Lead-carbon negative electrode with dendritic lead structure on surface as well as preparation method and application of lead-carbon negative electrode

Abstract

The invention discloses a lead-carbon negative electrode with a dendritic lead structure on the surface as well as a preparation method and application of the lead-carbon negative electrode, and belongs to the field of battery materials and energy storage. The preparation method of the lead-carbon negative electrode comprises the following steps: S1, dipping the lead-carbon negative electrode in a lead salt solution to complete adsorption of lead ions by a pore structure on the lead-carbon negative electrode; s2, keeping the material obtained in the step S1 in a wet state, and directly dipping the material in a sulfuric acid solution to complete the growth of layered lead sulfate on the surface of the lead-carbon negative electrode; s3, putting the material obtained in the step S2 into a dilute sulfuric acid solution added with a surfactant, and performing formation by adopting a formation procedure to complete construction of dendritic lead on the surface of the lead-carbon negative electrode; and S4, washing the material obtained in the step S3, soaking in a xylitol solution, and drying. The lead-carbon negative electrode with the dendritic lead structure on the surface has excellent electrochemical performance, and particularly shows outstanding sulfation resistance in a high-rate partial charge state, and the service life of the lead-carbon negative electrode in renewable energy storage application is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of battery materials and energy storage, and in particular relates to a lead-carbon negative electrode with a dendritic lead structure on the surface, and a preparation method and application thereof. Background Art

[0002] Lead-acid batteries, as a mature and widely used energy storage technology, have a history of more than 150 years. Since its invention in 1859, lead-acid batteries have been widely used in automobile starting batteries, backup power supplies, and UPS (uninterruptible power supplies) due to their low cost, high reliability and good safety. However, despite the many advantages of lead-acid batteries in traditional energy storage, they have also exposed some limitations in the context of renewable energy storage needs. With the continuous growth of renewable energy (such as wind and solar) power generation, the power grid needs equipment that can efficiently store and release electrical energy. However, the volatility and intermittency of renewable energy generation cause lead-acid batteries to frequently operate at high-rate partial charge states, which aggravates the sulfation of the negative electrode, that is, the formation of insoluble lead sulfate on the negative electrode of the lead-acid battery, resulting in capacity decay and significantly shortened battery life.

[0003] In order to solve this problem, researchers have proposed an improved solution - introducing carbon materials, namely lead-carbon batteries. In lead-carbon batteries, by introducing carbon materials into the negative electrode materials, the formation of insoluble lead sulfate can be inhibited to a certain extent, thereby reducing the sulfation phenomenon and extending the service life of the battery. The main functions of carbon materials in lead-carbon batteries are: 1) providing abundant active sites, which are conducive to the reduction and deposition of lead ions and improving the coulomb efficiency of the negative electrode under high current; 2) buffering the current through the double-layer capacitance effect, which can also improve the coulomb efficiency of the negative electrode under high current; 3) improving the conductivity of the negative electrode, thereby reducing the resistance to electron flow and improving the cycle performance of the battery; 4) hindering the formation of insoluble large particles of lead sulfate through steric hindrance. In the exploration and research of carbon materials, researchers have tried many different types of carbon materials, including activated carbon, carbon nanotubes, graphene, carbon fiber, etc., and have made certain progress.

[0004] China's invention patent publication number CN113871599B provides a lead-coated nitrogen-doped carbon composite material, its preparation and application in lead-carbon batteries. This carbon material improves the uniformity and density of lead loading by nitrogen doping, and has certain advantages in hydrogen evolution inhibition. However, the raw material cost of the technology is high and the preparation process is complicated, making it difficult to apply on a large scale.

[0005] The Chinese invention patent publication number CN112310392B provides a method for preparing a porous carbon / lead composite material with high stacking density. This technology combines chemical coordination and high temperature and high pressure lead infiltration to introduce a high proportion of lead species into the pores of the carbon material, thereby inhibiting hydrogen evolution and enhancing the uniformity of material mixing. However, this technology will significantly reduce the pore structure of the carbon material, thereby weakening the role of the carbon material in catalyzing lead ion reduction and double-layer capacitor buffering current.

[0006] China's invention patent publication number CN113948700A provides a monodisperse atomic cluster-activated carbon composite material and its application in lead-carbon batteries. This technology uses a polymer to pre-anchor lead ions, and then uses low-temperature solvent thermal reduction to load the lead atomic clusters on the surface of the carbon material to achieve the purpose of inhibiting hydrogen evolution. However, this technology is not conducive to the formation of a strong chemical bond between the loaded lead species and the carbon substrate, and thus performs poorly in the process of constructing the lead-carbon binary connection structure.

[0007] In summary, although the current research results show that carbon materials can effectively improve the performance of batteries, with the deepening of technology, there are still some problems that need to be solved: 1) In order to enhance the binding force between carbon materials and negative electrode active materials and inhibit the occurrence of hydrogen evolution reaction, researchers usually need to load lead on the surface of carbon materials. This extra step increases the complexity of the preparation process and also increases the cost; 2) Most of the existing research focuses on improving the cycle life of the negative electrode by changing the structure of carbon materials and the uniformity of lead loading, while ignoring the characteristics of the negative electrode surface that are most susceptible to sulfation. In fact, the surface of the negative electrode is the area most susceptible to sulfation, and its microscopic characteristics are crucial to the uniform reaction of the electrode body. However, in the current public reports at home and abroad, there is no technology that can deeply consider these details. Summary of the invention

[0008] Purpose of the invention: The first purpose of the present invention is to provide a lead-carbon negative electrode with a dendritic lead structure on the surface, which has a simple preparation process and excellent resistance to sulfation. The second purpose of the present invention is to provide a method for preparing the above-mentioned lead-carbon negative electrode with a dendritic lead structure on the surface. The third purpose of the present invention is to provide an application of the above-mentioned lead-carbon negative electrode with a dendritic lead structure on the surface.

[0009] Technical solution: The preparation method of the lead-carbon negative electrode having a dendritic lead structure on the surface provided by the present invention comprises the following steps:

[0010] S1, immersing the lead-carbon negative electrode in a lead salt solution to complete the adsorption of lead ions by the pore structure on the lead-carbon negative electrode;

[0011] S2, keeping the material obtained in step S1 in a wet state and directly placing it in a sulfuric acid solution for immersion, wherein the concentration of the sulfuric acid solution is lower than the concentration of the lead salt solution, so as to ensure that the lead ions diffuse into the solution at a relatively faster rate, thereby completing the growth of layered lead sulfate on the surface of the lead-carbon negative electrode;

[0012] S3, placing the material obtained in step S2 in a dilute sulfuric acid solution added with a surfactant, and performing chemical formation using a chemical formation procedure to complete the construction of dendritic lead on the surface of the lead-carbon negative electrode;

[0013] S4, the material obtained in step S3 is rinsed and immersed in a xylitol solution, and finally dried to obtain a lead-carbon negative electrode with a dendritic lead structure on the surface.

[0014] Furthermore, in step S1, the lead salt is at least one of lead acetate or lead nitrate; and the immersion time is 4-24 hours.

[0015] Furthermore, in step S1, the lead-carbon negative electrode contains 0.5-4% of rice husk-based activated carbon, graphene or carbon nanotubes.

[0016] Furthermore, in step S2, the lead ion concentration in the lead salt solution is 0.5-2 mol / L, and the concentration of the sulfuric acid solution is 0.1-0.5 mol / L.

[0017] Furthermore, in step S2, the immersion time is 1-3 hours.

[0018] Furthermore, in step S3, the surfactant is at least one of polyvinyl alcohol, hexadecyltrimethylammonium bromide and sodium dodecylbenzenesulfonate, and the concentration of the dilute sulfuric acid solution is 1.05-1.1 g / ml.

[0019] Further, in step S3, the parameters of the formation procedure are: 6 large pieces of positive electrode / 7 large pieces of negative electrode, the large piece is composed of 9 small pieces, and the acid is soaked for 1-2 hours after being put into the tank; ①16-24A charging for 1-2 minutes, standing for 1 minute, repeating the above steps 60 times; ②35-45A charging for 1-2 minutes, standing for 1 minute, repeating the above steps 60 times; ③18-25A charging for 6-9 hours; ④23-30A charging for 6-10 hours; ⑤12-20A charging for 1-4 hours; wherein, the mass of the lead paste of the positive electrode sheet is 96-108g, and the mass of the lead paste of the negative electrode sheet is 70-84g.

[0020] Furthermore, in step S4, the rinsing is performed with pure water until the pH of the washing water is 5-6; the concentration of the xylitol solution is 1.02-1.04 g / ml, the immersion time is 20-30 min, and the drying process is: first use 40-70°C hot air to blow dry the surface for 10-15 min, and then blow dry at 105-110°C for 1-1.5 h to control the moisture content to be less than 0.5%.

[0021] The present invention provides a lead-carbon negative electrode with a dendritic lead structure on the surface, which is prepared by the above-mentioned preparation method. The length of the dendritic lead structure is hundreds of microns and the diameter is tens of microns.

[0022] The present invention provides application of the lead-carbon negative electrode having a dendritic lead structure on the surface in the field of lead-carbon batteries.

[0023] Principle of the invention: In the present invention, the solidified lead-carbon negative electrode is firstly allowed to absorb lead ions in a lead-containing solution, and then immersed in a sulfuric acid solution in a wet state (to ensure the freeness of the lead ions), and the lead ions in the lead-carbon negative electrode and the sulfate ions in the solution are diffused toward each other at the solid-liquid interface to form layered lead sulfate on the surface of the lead-carbon negative electrode; then the lead-carbon negative electrode is immersed in a formation electrolyte containing a surfactant, and the surfactant is adsorbed on the surface of the layered lead sulfate to inhibit the diffusion of lead ions to other areas during the reduction process, and then a pulse formation process is used to form dendritic lead with lower surface energy; finally, the residual surfactant and dilute sulfuric acid are removed by washing, and the lead-carbon negative electrode with a dendritic lead structure on the surface is obtained after drying. The lead-carbon negative electrode prepared above is applied to lead-carbon batteries to significantly improve the performance of the batteries and extend their service life.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) Different from the prior art disclosed lead-carbon negative electrode design strategy, the present invention suppresses the sulfation phenomenon of the negative electrode for the first time by constructing a dendritic lead structure on the surface of the lead-carbon negative electrode; (2) The dendritic lead structure has excellent anti-sulfation ability, which can significantly delay the sulfation of the surface of the lead-carbon negative electrode, ensure the diffusion of the electrolyte, and realize the uniform reaction of the electrode body, thereby significantly improving the high-rate partial state of charge cycle number and rate discharge capacity of the negative electrode; (3) The process steps of the present invention have the advantages of low cost and convenience, and can further significantly improve its high-rate partial state of charge cycle life and rate discharge capacity on the basis of the original lead-carbon battery, and has good commercial value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope image of the surface layered lead loaded unformed lead-carbon negative electrode prepared in Example 1;

[0026] Figure 2 This is a scanning electron microscope image of the surface dendritic lead loaded lead-carbon negative electrode prepared in Example 1;

[0027] Figure 3 This is the scanning electron microscope image of the blank control group without lead-carbon negative electrode;

[0028] Figure 4 This is the scanning electron microscope image of the lead-carbon negative electrode formed in the blank control group;

[0029] Figure 5 This is a scanning electron microscope image of the lead-carbon negative electrode prepared in Comparative Example 3;

[0030] Figure 6 This is a scanning electron microscope image of the lead-carbon negative electrode prepared in Comparative Example 4;

[0031] Figure 7 This is a scanning electron microscope image of the lead-carbon negative electrode prepared in Comparative Example 5. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments and drawings.

[0033] Example 1: The method for preparing a lead-carbon negative electrode having a dendritic lead structure on the surface provided in this example comprises the following steps:

[0034] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0035] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 2 mol / L lead acetate solution for 12 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.1 mol / L sulfuric acid solution for 2 h.

[0036] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0037] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass of 96-108g) / 7 large pieces of negative electrode (lead paste mass of 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0038] S3: Post-treatment of lead-carbon negative electrode

[0039] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0040] Blank control group: The lead-carbon negative electrode provided in this control group was prepared as follows:

[0041] S1: The lead-carbon negative plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) and the commercial positive plate were immersed in dilute sulfuric acid (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (the mass of lead paste is 96-108g) / 7 large pieces of negative electrode (the mass of lead paste is 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0042] S2: Post-treatment of lead-carbon negative electrode

[0043] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0044] The microscopic morphology of the materials obtained before and after the formation of Example 1 and the blank control group was characterized. Figure 1-Figure 4 .Depend on Figure 1 It can be seen that after the unformed lead-carbon negative electrode was immersed in lead salt solution and sulfuric acid solution in turn, lamellar lead sulfate grew on the surface. Figure 3 The surface of the lead-carbon negative electrode in the blank control group did not have lamellar lead sulfate, which indicates that the diffusion-driven strategy proposed in the present invention can achieve the growth of lead sulfate on the surface of the lead-carbon negative electrode. By chemically converting the lead-carbon negative electrode with lamellar lead sulfate grown on the surface in a sulfuric acid solution with a surfactant added, the lamellar lead sulfate is gradually converted into a dendritic lead structure, such as Figure 2 As shown, this structure has better reactivity and resistance to sulfation. Figure 3 The lead-carbon negative electrode in the blank control group still has a granular structure after formation.

[0045] Example 2: The preparation method of the lead-carbon negative electrode having a dendritic lead structure on the surface provided in this example comprises the following steps:

[0046] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0047] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 1.5 mol / L lead acetate solution for 18 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.2 mol / L sulfuric acid solution for 1 h.

[0048] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0049] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing hexadecyltrimethylammonium bromide (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass is 96-108g) / 7 large pieces of negative electrode (lead paste mass is 70-84g) and allowed to stand for 2h, and then chemically processed according to the following process: ① Charge at 18A for 1.5min, stand for 1min, and repeat the above steps 60 times; ② Charge at 35A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 25A for 6h; ④ Charge at 24A for 9h; ⑤ Charge at 15A for 3h.

[0050] S3: Post-treatment of lead-carbon negative electrode

[0051] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0052] Example 3: The preparation method of the lead-carbon negative electrode having a dendritic lead structure on the surface provided in this example comprises the following steps:

[0053] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0054] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 1 mol / L lead nitrate solution for 24 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.3 mol / L sulfuric acid solution for 2 h.

[0055] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0056] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing sodium dodecylbenzene sulfonate (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass is 96-108g) / 7 large pieces of negative electrode (lead paste mass is 70-84g) and allowed to stand for 2h, and then chemically processed according to the following process: ① Charge at 22A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 22A for 7h; ④ Charge at 20A for 10h; ⑤ Charge at 13A for 4h.

[0057] S3: Post-treatment of lead-carbon negative electrode

[0058] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0059] Example 4: The difference from Example 1 is that 2% graphene is added to the lead-carbon negative electrode, and the preparation method is as follows:

[0060] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0061] The lead-carbon negative electrode plate added with 2% graphene (Jiangxi Jinkang New Material Technology Co., Ltd.) was immersed in a 2 mol / L lead acetate solution for 12 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.1 mol / L sulfuric acid solution for 2 h.

[0062] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0063] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass of 96-108g) / 7 large pieces of negative electrode (lead paste mass of 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0064] S3: Post-treatment of lead-carbon negative electrode

[0065] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0066] Example 5: The difference from Example 1 is that 2% carbon nanotubes are added to the lead-carbon negative electrode, and the preparation method is as follows:

[0067] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0068] The lead-carbon negative electrode plate added with 2% carbon nanotubes (Jiangxi Jinkang New Material Technology Co., Ltd.) was immersed in a 2 mol / L lead acetate solution for 12 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.1 mol / L sulfuric acid solution for 2 h.

[0069] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0070] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass of 96-108g) / 7 large pieces of negative electrode (lead paste mass of 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0071] S3: Post-treatment of lead-carbon negative electrode

[0072] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0073] Comparative Example 1: The difference from Example 1 is that no lead salt solution impregnation is performed, and the preparation method is as follows:

[0074] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0075] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in 0.1 mol / L sulfuric acid solution for 2 h.

[0076] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0077] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass of 96-108g) / 7 large pieces of negative electrode (lead paste mass of 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0078] S3: Post-treatment of lead-carbon negative electrode

[0079] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0080] Comparative Example 2: The difference from Example 1 is that sulfuric acid impregnation is not performed, and the preparation method is as follows:

[0081] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0082] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 2 mol / L lead acetate solution for 12 h.

[0083] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0084] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass of 96-108g) / 7 large pieces of negative electrode (lead paste mass of 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0085] S3: Post-treatment of lead-carbon negative electrode

[0086] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0087] Comparative Example 3: The difference from Example 1 is that no surfactant is used, and the preparation method is as follows:

[0088] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0089] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 2 mol / L lead acetate solution for 12 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.1 mol / L sulfuric acid solution for 2 h.

[0090] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0091] The lead-carbon negative electrode with surface layered lead sulfate growth completed in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass is 96-108g) / 7 large pieces of negative electrode (lead paste mass is 70-84g), and allowed to stand for 1.5h, and then chemically processed according to the following process: ① Charge at 20A for 1min, stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, stand for 1min, and repeat the above steps 60 times; ③ Charge at 23A for 7h; ④ Charge at 26A for 8h; ⑤ Charge at 17A for 2h.

[0092] S3: Post-treatment of lead-carbon negative electrode

[0093] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0094] Comparative Example 4: The difference from Example 1 is that a non-pulse chemical formation process is adopted, and the preparation method is as follows:

[0095] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0096] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 21 mol / L lead acetate solution for 12 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 0.1 mol / L sulfuric acid solution for 2 h.

[0097] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0098] The lead-carbon negative electrode with surface layered lead sulfate growth in S1 and the commercial positive electrode green plate were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (lead paste mass is 96-108g) / 7 large pieces of negative electrode (lead paste mass is 70-84g) and allowed to stand for 1.5h, and then chemically processed according to the following process: ①14A discharge for 0.5h; ②17A charging for 4h; ③23A charging for 6h; ④27A charging for 8h; ⑤17A charging for 2h.

[0099] S3: Post-treatment of lead-carbon negative electrode

[0100] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0101] Comparative Example 5: The difference from Example 1 is that the concentrations of lead acetate and dilute sulfuric acid are interchanged, and the preparation method is as follows:

[0102] S1: Construction of layered lead sulfate on the surface of lead-carbon negative electrode

[0103] The lead-carbon negative electrode plate added with 2% rice husk-based activated carbon (Jiangxi Jingang New Material Technology Co., Ltd.) was immersed in a 0.1 mol / L lead acetate solution for 12 h; the lead-carbon negative electrode after impregnation was taken out and immediately immersed in a 2 mol / L sulfuric acid solution for 2 h.

[0104] S2: Construction of dendritic lead on the surface of lead-carbon negative electrode

[0105] The lead-carbon negative electrode with layered lead sulfate growth on the surface in S1 and the commercial positive electrode green sheet were immersed in dilute sulfuric acid containing polyvinyl alcohol (1.05g / ml, 25°C) at a ratio of 6 large pieces of positive electrode (96-108g of lead paste) / 7 large pieces of negative electrode (70-84g of lead paste) for 1.5h, and then formed according to the following process: ① Charge at 20A for 1min, let stand for 1min, and repeat the above steps 60 times; ② Charge at 40A for 1min, let stand for 1min, and repeat the above steps 60 times;

[0106] ③23A charging for 7h; ④26A charging for 8h; ⑤17A charging for 2h.

[0107] S3: Post-treatment of lead-carbon negative electrode

[0108] The lead-carbon negative electrode obtained in S2 was rinsed with pure water (until the pH value of the washing water was 5-6), immersed in 1.02-1.04 g / ml xylitol solution at room temperature for 20 min, then dried with hot air for 10 min (to avoid subsequent drying and cracking), and dried in a 105°C forced air drying oven for 1 h (to control the moisture content below 0.5%).

[0109] The morphology of the lead-carbon negative electrode prepared in Comparative Examples 3 to 5 was characterized, and the scanning electron microscope images are shown in Figure 5-Figure 7 As can be seen from the figure, the surface of the lead-carbon negative electrode prepared in Comparative Examples 3 to 5 is still a granular lead structure, and a dendritic lead structure with stronger reactivity and resistance to sulfation has not been successfully constructed, which shows that the surfactant, pulse formation process and concentration of the impregnation solution are all crucial to the construction of the dendritic lead structure.

[0110] Application Example 1-Application Example 5 and Application Comparative Example 1-Application Comparative Example 5:

[0111] A method for preparing a lead-carbon battery comprises the following steps:

[0112] A 4V4Ah lead-carbon battery was assembled using the negative electrode plates of lead-carbon batteries according to the battery factory standard (three positive and three negative plates in a single cell, a separator thickness of 1.5 mm, and a single positive plate). 47 ml of acid (1.335 g / ml, 25°C) was added to each cell. A vacuum pressure acid injection machine was used to pump the acid to a vacuum pressure of 0.08 MPa for 6 seconds, and then the atmosphere was opened for 3 seconds, and this was repeated 3 times. The electrolyte contained 0.8% sodium sulfate.

[0113] Effect evaluation

[0114] 1. High rate partial state of charge cycle life detection.

[0115] The 4V4Ah lead-carbon battery was discharged to 50% state of charge at 1C current, and then charged at 2C rate for 60s, left to stand for 20s, and discharged at 2C rate for 60s until the discharge voltage was lower than 1.7V. The number of charge and discharge cycles was tested. The technical effect of charge and discharge times is shown in Table 1.

[0116] It can be seen from Examples 1 to 5 and the blank control group (plates with 2% rice husk-based activated carbon added without further treatment) in Table 1 that the construction of the dendritic lead structure on the surface of the lead-carbon negative electrode significantly improves the cycle life on the basis of the original lead-carbon negative electrode. The differences in cycle life in Examples 1 to 3 indicate that the process parameters have a certain influence on the construction of the dendritic lead structure. The cycle life of Comparative Examples 1 to 5 is basically the same as that of the blank control group, which shows that the adsorption of free lead ions, impregnation with sulfuric acid solution, addition of surfactants in the formation solution and pulse formation in the process are all crucial to the construction of the dendritic lead structure on the surface of the lead-carbon negative electrode. Finally, in Examples 4 and 5, lead-carbon negative electrodes with different carbon materials added were selected, and significant performance improvements were achieved, which illustrates the versatility of the present invention.

[0117] Table 1

[0118] Group Cycle times (times) Group Cycle times (times) Example 1 16324 Comparative Example 1 5725 Example 2 15216 Comparative Example 2 5213 Example 3 14894 Comparative Example 3 5695 Example 4 14968 Comparative Example 4 4979 Example 5 18752 Comparative Example 5 4237 Blank control group 5039

[0119] 2. 80% DoD deep cycle life test.

[0120] The 80% DoD deep cycle life test is used to analyze the cycle stability of the battery under high current deep cycle conditions. After full charging, discharge at a current of 0.4C for 8 hours, let stand for 2 hours, charge 3.36Ah at a constant voltage current limit (4.7V / 0.3C), let stand for 2 hours, and after the above cycle is repeated 150 times, the battery is discharged to 1.75V at 0.2C, and the capacity retention rate after 150 cycles is calculated. The test results are shown in Table 2. It can be seen from Table 2 that compared with the blank control group, the construction of surface dendritic lead in Examples 1-3 further improves the 80% DoD deep cycle capacity retention rate of the negative electrode on the basis of the original lead-carbon electrode. Combined with Examples 4-5, it is found that this strategy is also applicable to lead-carbon negative electrodes with added graphene or carbon nanotubes, indicating that the present invention has a certain universality.

[0121] Table 2

[0122]

Claims

1. A method for preparing a lead-carbon negative electrode having a dendritic lead structure on the surface, characterized in that: The following steps are involved: S1, immersing the lead-carbon negative electrode in a lead salt solution to complete the adsorption of lead ions by the pore structure on the lead-carbon negative electrode; S2, keeping the material obtained in step S1 in a wet state and directly placing it in a sulfuric acid solution for immersion, wherein the concentration of the sulfuric acid solution is lower than the concentration of the lead salt solution, so as to ensure that the lead ions diffuse into the solution at a relatively faster rate, thereby completing the growth of layered lead sulfate on the surface of the lead-carbon negative electrode; S3, placing the material obtained in step S2 in dilute sulfuric acid added with a surfactant, and performing chemical formation using a chemical formation procedure to complete the construction of dendritic lead on the surface of the lead-carbon negative electrode; S4, the material obtained in step S3 is rinsed and immersed in a xylitol solution, and finally dried to obtain a lead-carbon negative electrode with a dendritic lead structure on the surface.

2. The preparation method according to claim 1, characterized in that: In step S1, the lead salt is at least one of lead acetate or lead nitrate; and the immersion time is 4-24 hours.

3. The preparation method according to claim 1, characterized in that: In step S1, the lead-carbon negative electrode contains 0.5%-4% of rice husk-based activated carbon, graphene or carbon nanotubes.

4. The preparation method according to claim 1, characterized in that: In step S2, the lead ion concentration in the lead salt solution is 0.5-2 mol / L, and the concentration of the sulfuric acid solution is 0.1-0.5 mol / L.

5. The preparation method according to claim 1, characterized in that: In step S2, the immersion time is 1-3 hours.

6. The preparation method according to claim 1, characterized in that: In step S3, the surfactant is at least one of polyvinyl alcohol, hexadecyltrimethylammonium bromide or sodium dodecylbenzenesulfonate, and the concentration of the dilute sulfuric acid solution is 1.05-1.1 g / ml.

7. The preparation method according to claim 1, characterized in that: In step S3, the parameters of the formation procedure are: 6 large pieces of positive electrode / 7 large pieces of negative electrode, the large piece is composed of 9 small pieces, and the acid is soaked for 1-2 hours after the tank is lowered; ① 16-24A charging for 1-2 minutes, standing for 1 minute, repeating the above steps 60 times; ② 35-45A charging for 1-2 minutes, standing for 1 minute, repeating the above steps 60 times; ③ 18-25A charging for 6-9 hours; ④ 23-30A charging for 6-10 hours; ⑤ 12-20A charging for 1-4 hours.

8. The preparation method according to claim 1, characterized in that: In step S4, the rinsing is performed with pure water until the pH of the washing water is 5-6; the concentration of the xylitol solution is 1.02-1.04 g / ml, the immersion time is 20-30 min, and the drying process is: first use 40-70°C hot air to blow dry the surface for 10-15 min, and then blow dry at 105-110°C for 1-1.5 h.

9. A lead-carbon negative electrode having a dendritic lead structure on the surface obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The length of the lead dendrite structure is hundreds of micrometers and the diameter is tens of micrometers.

10. Use of the lead-carbon negative electrode having a dendritic lead structure on the surface as claimed in claim 9 in the field of lead-carbon batteries.

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